In message "[ruby-talk:12854] problem with cvs access"
    on 01/03/19, Max Ischenko <max / malva.com.ua> writes:

|What did I do wrong?
|
|$ cvs -d :pserver:anonymous / cvs.ruby-lang.org:/home/cvs login
|(Logging in to anonymous / cvs.ruby-lang.org)
|CVS password: <type guest>

It's "anonymous", not "guest".
See http://www.ruby-lang.org/~knu/cvsrepo-guide.txt